Specifically, the present invention is advantageously, but not exclusively, applied to an apparatus structured for being able to dry a paint or painting product in general applied onto a motor vehicle or component parts thereof to which explicit reference will be made in the following description without therefore loosing in generality.
As known, the operation of some apparatuses currently employed for drying paints applied onto the bodywork or bodywork parts of a motor vehicle, is essentially based on the principle of transmitting heat to the paint itself “by convection”. Such apparatuses indeed comprise generating a high temperature air flow directed towards the motor vehicle. Such apparatuses typically comprise a drying oven or booth adapted to accommodate a motor vehicle on the bodywork of which a paint to be dried has been applied; and a hot air generating circuit which provides for heating up the air and blowing the heated air towards the motor vehicle, so as to determine the paint drying.
The aforesaid apparatuses are particularly disadvantageous because relatively long times are required for completely drying the paint with consequent, relatively high energy consumptions.
Apparatuses in which the operation is essentially based on the principle of transmitting heat to the paint “by radiation” are also known. Such apparatuses emit infrared radiation beams towards the motor vehicle. Such apparatuses typically comprise infrared (IR) lamps structured to emit infrared radiations in the so-called “short-wavelength infrared” band, and specifically infrared radiations having a wavelength in the range of about 2-3 μm, or infrared lamps structured to emit radiations in the so-called “medium-wavelength infrared” band, and specifically infrared radiations having a wavelength in the range of about 4-6 μm.
The infrared radiations generated by the “short-wavelength” IR lamps are able to transfer a percentage of radiated energy between about 8% and 12% to the paint molecules, thus activating a cross-linking process of the molecules themselves, i.e. a process which leads to the formation of strong bonds between the paint molecules, while the remaining percentage of energy is dispersed through the body of the object onto which the paint is applied. The drying process is carried out by the convective exchange between the body and the layer of paint. The completion time of the paint cross-linking process is thus variable because it depends on both the material of the body and the thickness of the applied paint layer. Therefore, in addition to being variable, the total paint drying times are also rather long due to the inevitable dispersion of heat in the body.
Instead, with regards to the apparatuses provided with “medium-wavelength” IR lamps, about 40% of the radiated energy is dispersed into the external environment and partially given back to the body by means of a rather slow convective process, while the radiated energy which reaches the layer of paint is withheld by the external surface of the body which, by conduction, transfers it therein. In this case, the type of material of the body does not affect the total drying time, which however is disadvantageously very long.